Compass



R. C. BURT Aug. 3, 1948.l

COMPASS 2 Sheets-Sheet l Filed Nov. 29, 1943 Invenor HUBERT KEUR?hef-:IT

l4 gglllllulm- Agent R. C. BURT Aug. 3, 1948.

COMPASS Filed Nov. 29, 1943 2 Sheets-Sheet 2 Inventor HUBERT CHUR? AgentPatented Aug. 3, 1948 2,446,253 .coMPAss @Egbert C,r Burt, Pasadena,Calif., assignor to Lockheed nimmt Corporntinn. iiibnnli, .QetiifAppiication November 29, 19.43j, :S,lT\ia/1N9. 512,215.

.4 mainte.

invention teintes to. compases, and Pefrtieular- .referenne to.natyigaitionel, minnen@ useful on mettait.

et .Conventinnnl ,fmenetio sommes. .is need in on aanplant; it.. is.snbieot itunefnuzit error known as northerlyg Iig conventionalteniinese ,-operttewn the empnnent @f the innerietio rfaield and whentno airplane :beanies .during .a turn, the piene of ...eoinpn S .oetitd11s tilted with :respect 11o .thehun-Montoilietilting oi tneoaitd.causes the needleto. be fee, @kunen-by the -t/.ertioel comf none-nt of.the .eartiis :magnetic .nieid with unf dnsirebl.. l. einer .Assumingthe aime; e "tO .he .in fthe noithernheniisphene .and I01.10 ine n.neiiiheilfy when it makes. o bnnked nuten, the needle-Qt the.oom/.entionail .com-

lliaise .-.s'winges downwardly A.nt n .ratte determined by :thetcnoraoteristios tno composait-he .eantnis megrietiofeldfafnnlthe.oiegiiee tof thexloank. The

needle tney turn taeterithenthelairniane, itmey turn @tithe .same ratene he tainniene, .out may .elower then the nir-pleine. depending uponthepaittieu'ler .heading @i the eirnlnnethe angie or henk, period@ ithe@nel .dineotionnf tno turn; .and athiis .tndineteoaiqtnrn .iny `.thewrong direction, indicate no y; .or :e slow-.er iturn 41n the ...correctdirec northerly turning ern-0r .nernileirs lthe pieeil .magnetic..oornpass fun- Reliable end `rmentip'1o.t.s.- tiene -eone -into a spinand crashed on this .neemt-nt.,

' .Itis an .imnortnntnnaeot of :.tnopresent invention =to pr-.onine@navigational magnetic .oompass .suitable r use-,onnir-.citefn .and.other nef. nietes, .that is ,not ,subect :to "northerly .turning erroriduring .notnnnl .or ordinary maneuveringand-Lhexetoneprondes.estrucreading-.undertnractielaiiy fali-oonditinnsof -ztnnning :and ybanking '0f thergft.

Another oplegt gf his invention sismo Vprovide a goxnpas of .the.Qhagfater .n.eferred tto fin which the magnetic needle. .foesnmes andmetint'ains a position @parallel with .-tne .ereiiftzhs'.magnetic mutt,entirely independently@ tithe .ihoitizong :and inneserves thus iattitudet-,or ,lponitnn 'throughout yall ordinary -nr troutne imanentteiine .nffthe airplane. 'rheabilitytotthenneodi to emgm inparallelism with the,eaifthemegnetio .siinxisnhetentially one visites .the nortneiilyturning, onor" 'inherent in conventional .eompaseesf .Another ehieetoofhs,.f.i.nii.eniion is to intent/ide a .compnss ,of ythe.-eiieiiete,,termentinned which one .needlogmnybe eaeeiirett-elyndynafinienl1y balanced.Sp that rittheis nofatenseny to turn due toncneleietion ieieots.

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. y.2 .Another .emi .imminent .oleiei iiiA ythe tion. is., Jie. nnoviiie.eemtieee .of interred te .tnt ooeietes.; .t0 indieie theenevle nime.netie @Bip f 11.1 which :tneleiiii nein ,L .LQ Another and 1.5nienntifie iepifovdeq on .my l @generate-with the nein-er-.eooie so inety.the .cm1 neee...ii.1.ey yer.

356.0."o .-.end .henri eti@ A s .and indicia t9. he tend .tqgeiie fromnnsition 2.5 tlietonmpetee.- f

inqtiier .-.Qb.iee...t Qf. the inventinn is. 5to. nnoxnd omheen .elmines Qi inferred to om?. hdyine' a ,esiing .tiet ..effetive ,ontienlineens im .ieeilitetine teviewine, i. needieoroeome. ao lase @einteigne. @generally ...ontiooi nit-ie. Y v

In. uriner obieot nf this :invention is to me: visie eoeoninetes'ef.iii-e eh .erred to that. menne embodied in einen 35 mtiolpnitto ,berrapil in s action.

nel. Qbieie :and .fieetiiiee 9i the .invention meile @viennent ahy the.afpllewine idotnilod deeeiintion .of fe. ftytpieel yillustieniveembodiment. tnxooghont .Wnieli .@.eeiintion .ireeifonsie is. fxnesie. 0t thac'companying drawings in which,

` .Eieurezl netspeiive .new .of .the @originates 0f itiiepinweniien withtine env pe .binnen @my finish wftheinteiinel neri-ein eleveiiien.: Co,is @neutral vertieel l...et ...ien seetionol 45 viewer theetiinpese:

` Figline 3 is' a .fleeinenieryneietied Yiew...f thenrierneridftne-imnee that @lineare theiiein;

miennes 1 attriti 5 ...ete .enlarged transverse .oieteiledeeilionnlviews :teken .es indieeted Minets 50 4%.4andrgie-tfresiieetively,.on.Fien

.Figline .o is nn @enlarged longitudinal neieiiedseoiinnelniewnftthe:needle-endete. mounting. e ,.flgnegornpagsofvfolfieinvention may be ,varied .to @51am .it ifQI Ldierent`.Etpliilicatziorls tand. .inst/tillen., 55. tign, vinthe vdrwzings have`-illusi'mztted a,

supported in the frame I2 for rotation about a horizontal axis andh'avinga scale C for. indicating the magnetic dip.

The mounting II) may besuch that it adapts the compass for attachmentto-any required or selected support. In the construction illustrated,the mounting II) is such that the compass may be attached to a ceilingor vertical wall of a cabin or cockpit. yThev mounting` shown includes amain member I4 provided with a mounting bracket I5. Th'ebracket I5 issecured toa vertical support 1B by screws or bolts IT. :The member yi4extends horizontally from the bracket Ii 5 and has a central verticalopening ISL 'The opening I8 is counterbored or enlarged from its upperend to have a socket I9l and an upwardly facing annular shoulder 20. Themouth'oi the socket I9is closed by a removable plate 2I. 1

The venvelope or case II serves to house the principal compass elementsand carries the course setting scale A. In the construction illustrated,thel case I I is a hollow cylindrical structure comprising a'cylindricalside 'wall 22, a top closure 23, Vand a bottom closure 24. The case IIis formed of glass, transparent plastic, or other suitable 4transparentmaterial. The top and bottom closures 23 and 24 are sealed with andsecured'to the. ends of the side wall 22 `by cement, or the like. Thecase I I is suspended from the mounting Ito be almost entirely exposedto view. The side wall 22 is rotatably received in theopening I8of themember I4 and the top closure 23 projects beyond the side wall to bearon the'sh'oulder 20 and thus suspend `the case. The case II/contains abody of colorless or transparent 'licpiid to dampen movement of thecompass elements. A filling opening is provided inthe top closure 23 tofacilitate'lling of the case and the opening 'is normally closed by ascrew threaded plug 25. The:

plate 2I is removable to give free access to the plug' 25 and thefilling opening. Means is provided to hold the projecting top'closure 23seated on the shoulder 20. This means may comprise a bowed leaf springA26 bearing between the plate 2I and-the top `of the plug 25. The'spring26 serves to resist or prevent upwardmovement of the-`case 22withrespectto the mounting means l0. f lThe course setting scale A may bein thenature of an annular ilange depending from av disc 2'I.

Any suitable means may be employed vt'osecure the-scale A in the case II I n the simple structure illustrated, pins 28 project from thefscaleand are secured in sockets inthe side wall 22 to fix the scale inthecase. The exterior of the scale Ais suitably calibrated in degreesy andbears the usuali: compass characters N, E, S,'and W. The scale Acooperates with a Vernier scale 9 and reference'line 29 on the mountingmember I4. The-compass is positioned so that the line 29 lies. inthelcentral longitudinal axis ofthe airplane. The Vernier scale B andreference line 29 are provided on a sloping forward face oimemberL 4 I4,the scale 9 extending from each' side of the line. The scale A has acounterpart scale A1 formed on the external surface of the case directlybelow the scale 9 and line 29. The scales A and A1 are identical intheir calibrations and both extend 360 around the case. The scale A1 isa continuation of the scale A to aid in reading the 4scale A With thereference line 29 and Vernier scale '9'. 'n setting the course, the caseII is turned'to' bring the selected course calibration of the scales Aand A1 into registration with the line 29. The Vernier scale 9facilitates the accurate setting of the scales A and A1 and the case II.

Thev invention includes means for readily adjusting or rotating the caseII to set the scale A. In the embodiment of the invention illustrated,this means includes aworm Wheel 30 xed to the top closure 23 to bewithin the socket I9. A worm 3I is rotatable within, a horizontaltangential opening 32 in the member I4 and meshes with the wheel 30. Theshaft of the worm 3I projects from the member I4 and has a knurled knobor hand wheel 33 to facilitate rotationof the worm; It will be apparenthow the hand wheel 33 may be manipulated to rotate the case I I for thepurpose of setting the scale A. Y

The frame I2 is'mounted within the case II and serves to support theneedle I3 and the scale B. The frame I2 comprises an upper disc 34having a downturned annular iiange which constitutes the scale B. Thedisc 34 and the scale B may be substantially identical with the disc 21and scale A. The disc 34 is arranged immediately below the lower edge ofthe scale A so that the scale B is directly below the scale A. ThescaleB is provided with calibrations identical Withthe calibrations on thescale A and continuing throughout the full 360. The frame I2 furtherincludes two spaced vertical members 35 having ears or flanges 36 ontheir upper ends securedto the underside of the disc 34. The members 35are diametrically opposite and are provided at their lower ends withinturned ears 37. A transverse or horizontal member 38 extends betweenand is secured to the ears 31. It may be preferred to have .thehorizontal member 38 bear on the upper sides of the'inturned ears. 38isiormed of transparent material so that it does not interfere with theview of the dip scale" C as will later become' apparent. The frame I2lis supported for rotation about avertical axis which is preferablycoincident with the axis of rotation of the case' II. Any suitable formofl gimbals `or bearings may Abe employed to mounty th'e frame I2 in thecase I I. I have shown vertically disposed pointed vpins 39 on the disc34 and' horizontal member 38 cooperatingwithsocketed jewels or blocks 40on the disc 21 and bottom closure 24. These bearings support the frameIZfor rotation witlra minimum of friction.

The needle I3 is supported in the frame I2 forV free rotation about ahorizontal axis, that is about an vaxis normal 'to the axis of rotationof the extends through a sleeve 42. be square or rectangular intransverse cross section and its opening 43 is proportioned to receivetheneedle I3 for adjustment. As best illustrated in Figures; 5 and 6ofthe drawings, the opening 4351s transverselyr elongated in onedirection toy permit @bodily movement oft the needle I3 with' respect tothe sleeve in a transverse direction'as The member' altes-gasa.

well". asr aflongitudinal. direction. Thei-needleef I 3; may `.be iadjustedrboth.longitudinally and laterally: with respect f tov the.ysleeve: l 2;.. and. ther invention` provides .means if or :setting or:securingthe needle: .its adjusted. position'.j The a means: includes abowed;A leaf J spring 44al partially. recessed.. in the wallhof the.openingI 43,; and" bearing against;v a.

Ay set fscrewv 45iis threaded.: throughan` opening inthe wallsof v.thesleeve 423 tof clamp.- against the opposite surface of. theI needle.It-:willbe seen from an: inspection-off Eigures l'andf fifhowfthelneedle 'I 3may-y be readily adjusted with respect to the sleeve421andthen surface of. `the.- needle.

setforksecured-in the-adjusted position by means of the screw 45.

The ability to adjustthev needle AI 311s important because it allows theneedle to be dynamically balanced and therefore resistant to orunaffected by acceleration effects. If. desired, the needle supporting4sleeve'42 may be formed of a transparentzmaterial. needley |32 for.rotation about a. horizontal. axis mayfcomprise .pointedbearinggpinsi-46 projecting from opposite sidesofthe sleeve42rand engagingiir-recessedifblocks v4.'I fixedto. the inner: sidesv oftherframe:members.35.V The common axis `ofthe vbearing pins 43.. isnormal to the common: axis of the bearingpins `39-and is midway betweenther-ends voffthe sleeve. 42.

The magnetic dip-scale: C is secured to the needle I3 to move therewith.As illustrated, the

scaleC may be in the form of 7a ring or annulary drum direct-lyVsecu-redfat diametrically opposite p'oints'tothe ends-of theneedjle I3;vTheexternal surface of the scale C is suitably calibrated in degreeswhich may be read with a reference point or line on the frame I2. Asbest illustrated in Figure 4 of the drawings, I have provided a centralhorizontal line 49 on the upper surface of the frame member 38 with anarrow 48 extending laterally from the line 49. The dip scale C isarranged and proportioned to rotate within the frame I2 withoutinterference, but its lower portion moves in close proximity to theframe member 33 so that its calibrations are close to the line 49. It isdesirable to prevent the needle I3 and dip scale from rotating past thevertical in the event of violent maneuvering of the craft. For thispurpose I may provide a stop pin 53 projecting from the dip scale C andadapted to strike the member 38.

The invention includes means whereby the pilot may readily View the dipscale C and they reference line 49 along a horizontal axis to determinethe magnetic dip. The information thus gained is useful in roughnavigation and discloses whether the airplane is in level ight. Amagnifying prism 58 is arranged below the case II. Spaced arms I projectdownwardly from the mounting member I4 and adjustably support the prism58 so that it may be moved to the correct angle. The prism 50 ispositioned so that its magnifying convex surface is substantially normalto the longitudinal axis of the airplane. As diagrammaticallyillustrated in Figure 2, the reference line 49, the lower portion of thescale C, and the arrow 48 may be viewed along a horizontal axis from infront of the prism. The arrow 48 is useful in indicating the generalmagnetic azimuth.

From the above detailed description it will be seen that I have providedan overhead course setting compass that serves to give magnetic dipreadings in addition to the course readings. The

The meansxfr supporting; the I present in conventionaly com-passes.Owing to the fact that the compass of the inventionre-f mains-true andaccurate throughout al1=` turnsf during ordinary'iiight, it isunnecessary to-employa gyroscopic turn indicatorA and this latterinstrument may :be -eliminated from the aircraft.'

When# assembling the compassthe needle I3 may@ be accurately' balanceddynamically toremain'i unaifected by acceleration'eifects with the:result that the-compass is extremely steady'and reliable;

The magnetic dip indications providedby' the"l compass'v are -valuableinnavigating theairplane; .li-particular feature-and advantage of thisinven metallic parts thereof A'are usually at a minimum:

In this connection it is to be observed that "allof the scales of thecompass are fullyand' easilyread from below the level of thecompassbody'.

From the above description it'will' beseenthat I have'provideda simpleandvery'eifective over-` headv compass' particularly well: suited-forIuseY in.

aircraft.' The compassis' easily set with great'aC-l curacy bysimplemanipulation-'of'tlieknob 33:V` The Vernier scale 9 cooperating with thescales A and A assures extremely accurate setting of the compass even inembodiments where the compass is very small in size. The full circlescales A, B, and A facilitate reading of the compass from any positionand the reflector 50 makes it possible to determine at a glance themagnetic dip.

Having described only a typical form of the invention, I do not wish tobe limited to the specic details herein set forth, but wish to reserveto myself any variations or modifications that may appear to thoseskilled in the art and fall within the scope of the following claims.

I claim:

l. A compass comprising overhead mounting means, a primary supportcarried by said means for rotation about a vertical axis an-d to dependfrom said means, a course setting scale on the primary support, yasecondary support carried by the primary support for rotation about saidvertical axis, a magnetic azimuth scale on the secondary support forcooperating with the course setting scale, a reference mark on thesecondary support, a magnetic needle, means for mounting the needle onthe secondary support for rotation about a horizontal axis to remainparallel with the earths magnetic ux, the needle being operable to turnthe secondary support, and a dip drum scale movable with the needleabout said horizonta1 axis and cooperable with said mark to indicate themagnetic dip.

2. A navigational compass comprising a case, means suspending the casefor rotation about a vertical axis, a course setting scale on the case,a frame supported in the case for rotation about said axis and having amagnetic azimuth scale for cooperating with the course setting scale, amagnetic needle mounted in the frame for rotation about a horizontalaxis so as to remain parallel with the earths magnetic flux, the needlebeing operable to turn the iframe, areference mark on the lower portionof the frame, and a drum type scale movable withthe needle about saidhorizontal axis and cooperable with the reference mark to indicate themagneticidip, at least the lower portion of the casev being transparentso that the reference markfand the drum type scale are visible from theexterior of the case.

3. A navigational compass comprising a case, means suspending the casefor rotation .about a vertical axis, a course setting scale on thecasera frame supported in the case for rotation about said axis andhaving a magnetic azimuth scale for cooperating with the course settingscale, a magnetic needle mounted in the frame for rotation about ahorizontal axis so as to remain parallel With the earths magneticwilux,the needle being operable to turn the frame, a reference mark on thelower portion of the frame, a drum type scale movable with the needleabout said horizontal axis and cooperable with the reference mark toindicate the magnetic dip, thecase being constructed of transparentmaterial so the azimuth scale, the reference mark and said drum typescale are visible from the exterior of the case, and a reflectorsupported below the case for reflecting the images of the reference markand said drum type scale forwardly so that all of said scales and thereference mark may be viewed from a position in front of the case.

4. A navigational compass comprising a case, means suspending the casefor rotation about a vertical axis, a course setting scale on the case,a frame supported in the case for rotation about said axis and having a,magnetic azimuth scale for cooperating with the course setting scale, avsleevemounted in the frame for rotation about a hori zontal axis, a,magnetic needle initially shiftable both axially andtransversely in thesleeve, Ya spring inthe sleeve bearing on one side of the needle to urgeit transversely in one direction, and a screw on the sleeve for actingon the other side of the needle to urge it transversely in the otherdirection and `to retain the needle in the axially adjusted position,the needle being operable to turn the frame about said vertical axis andbeing free to remain parallel with the earths magnetic flux.

ROBERT C. BURT.

REFERENCES CITED The following references are of record in the le of'this patent.: f

'K UNITED STATES PATENTS Number Name Date 682,585 Cotter et a1 Sept. 10,1901 1,216,953 .Creagh Feb. 20, 1917 1,533,683 Abbot Apr. 14, 19251,961,312 ViQn June 5, 1934 2,087,086 DeBeeson July 13, 1937 2,116,103DeBeeson May 3, 1938 2,118,082 Hammond May 24, 1938 2,215,622 SperrySept, 24, 1940 FOREIGN PATENTS Number Country Date 13,176 Great Britain1850 407,946 Great Britain 1934

